Fraser Horton
Fraser Horton
Last Updated on August 30, 2021

If you’re a cannabis grower, then you know that the soil you use is an important factor for the health of your plants. However, only rarely is the soil enough to keep the plants going in the long run and help them grow big.

Many growers of marijuana, and any other plant, for that matter, know that for the best results, you need to use a nutrient solution or organic fertilizers in conjunction with the potting soil, and for hydroponics (coco coir, rock wool), it’s basically obligatory.

Whatever growing medium you use, fertilizing your marijuana plants with the right nutrients will help them flourish, otherwise, you risk wasting time and effort and ending up with unhealthy plants and low-THC buds. So, to learn more about what nutrients your plants need just keep reading, below we have everything nutrient-related covered.

What Are the Essential Cannabis Nutrients?

Whatever the grow medium, the most important elements for growth that cannabis plants need during the vegetative growth phase are light, carbon dioxide, water, and nutrients. Light and carbon dioxide are absorbed by the chlorophyll and the stomata present in the leaves, while water and nutrients are absorbed through the roots.

When marijuana seedlings are planted after the germination process they have enough fuel to last them while they’re developing their cotyledons and start growing the taproot. At this point, they don’t need extra additives.

But once the process of root growth is over and the plants’ roots are strong enough, they will have used up all their fuel and will be in need of different nutrients, and this is when the grower steps in. It’s a crucial step of the process because if you don’t provide enough, you’ll soon start seeing nutrient deficiencies.

As a first-time grower, always make sure you purchase high-quality fertilizers with the best nutrients and follow the feeding schedule diligently as your plants will get used to it and you don’t want to interrupt the cycle.

Healthy cannabis plants require certain nutrients for better plant growth and to help them strengthen their roots, produce bigger yields, and make the best of their chemical composition. These nutrients generally fall into two categories – macronutrients and micronutrients, which are nearly equally important for the plant. Here’s a breakdown of the two groups.

Macronutrients

Macronutrients are also known as NPK, which refers to Nitrogen (N), Phosphorus (P), and Potassium (K), and your plants need them in large quantities. You’ll often find their values and the NPK ratio printed on the labels of fertilizer products – the higher the number, the higher their concentration.

Sometimes cannabis needs some nutrients more than others depending on which stage of growth it’s in, but also to correct any nutrient imbalances that may appear during its life cycle. However, overfeeding your plants with large amounts of nutrients is not recommended as it may lead to buildup and nutrient burn.

Nitrogen

Nitrogen is a crucial nutrient for the cannabis plant during its life cycle, but it’s even more essential during the vegetative stage because it plays a part in the plant’s development. It is needed for photosynthesis because it’s a constituent of chlorophyll, and without it, the photosynthesis process won’t be possible.

In other words, it won’t be able to transform light into energy, which will result in stunted growth. Additionally, Nitrogen is found in ATP, which is the main molecule responsible for storing and transferring energy in cells.

Nitrogen is also found in the essential amino acids of the cannabis plant. Amino acids are organic compounds that bind together to form proteins that serve as the building blocks for a healthy plant.

Deficiencies in Nitrogen will show up as faster yellowing of the leaves, especially the older ones, as well as slowed down growth. 

Phosphorus

The main role of Phosphorus is to promote the germination of seeds, to help with the seedling and root development. This nutrient is a key factor in producing healthy and vibrant buds during the flowering phase because it participates in the development of terpene resins.

Another role that Phosphorus has is to help with the uptake of other nutrients. Without it, your crops will end up with underdeveloped root systems and might have difficulty flowering.

If your plants become deficient in Phosphorus, you’ll start noticing purplish hues and seared edges on the smaller leaves. They may also start drying very quickly and your plants’ growth will seem to stagnate.

Potassium

Potassium is important during the flowering stage because it helps to grow healthy buds. In addition to this, it also plays other roles. It regulates the concentrations of salt and water in the plants by controlling the intake of water and carbon dioxide through the stomata. It also plays a part in the production of the ATP molecule that stores energy.

Deficiencies in Potassium also cause a slowed growth rate and your cannabis plants may seem burnt because they’ll have brown tips and edges with curled margins. 

Micronutrients

The micronutrients that your crops need are also very important for healthy growth. Even though they are needed in smaller quantities than macronutrients, they are still vital for maintenance. They are also included in all fertilizers but in smaller concentrations. Deficiencies in micronutrients are rare, but when they happen, it negatively impacts the plant.

Calcium

Calcium’s (Ca) role is to hold together the structure of the cell walls and membranes. It helps to strengthen the stems and roots of the plants. If there’s a lack of Calcium, the leaves will be rusty and distorted and the roots will have weak tips and won’t be fully developed.

Magnesium

Magnesium (Mg) is the key to the formation of chlorophyll and without it the plant won’t be able to create carbohydrates out of light. Deficiencies result in the yellowing of the older leaves as well as discoloration of the veins.

Sulfur

Sulfur (S) also has a role in the formation of chlorophyll, as well as the production of proteins, enzymes, and vitamins, making the plant less prone to disease. Sulfur deficiencies show up as stunted growth and deformation of the leaves which are rolled upwards and get stiff before they fall off.

Manganese

Manganese (Mn) is very important for the uptake of Nitrogen, as well as the production of enzymes. It plays a role in reproduction by assisting germination and the growth of pollen tubes. Manganese deficiencies will cause either yellowing of the leaves or white or gray spots.

Boron

Boron (B) helps to support cell walls and it helps to form the stalks and stems of the plants. It also prevents Calcium from becoming insoluble and helps the cells with water consumption. Boron deficiencies result in Magnesium and Potassium deficiencies, and the buds may become malformed before harvest time. 

Molybdenum

Molybdenum (Mo) plays a role in the production of proteins. Deficiencies in this nutrient are quite rare, but if you notice the middle leaves of your plant have started to turn yellow, it’s likely it needs Molybdenum.

Bottom Line

Other than light, carbon dioxide, and water, the essential elements that your marijuana plants need for healthy growth – micronutrients and macronutrients – are also crucial to their life cycle. Whether you’re an experienced grower or not, or whether you use hydro or organic soil in your grow room, providing your crops with the best nutrients should be a priority.

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